High quality heteroepitaxial AlN films on diamond.

Heteroepitaxial AlN films grown on (100)- and (111)-oriented diamond (C_α) substrates by plasma-induced molecular beam epitaxy have been investigated by x-ray diffraction (XRD) and atomic force microscopy (AFM). High quality epitaxial growth of almost strain-free wurtzite AlN is observed for both orientations. For the AlN/C_α(111) heterostructures, the epitaxial orientation relationship (0001)[1010] AlN∥(111)[011] C_α is obtained. However, a significant fraction of up to 20% of the epitaxial layer is oriented differently with (1011) AlN∥(111) C_α. In case of AlN on C_α(100), a double-domain structure with either (0001)[1010] AlN^I∥(100)[011] C_α or (0001)[1210] AlN^II∥(100)[011] C_α is found. The linewidths of the XRD ω and 2θ/ω scans of the symmetric AlN 002 reflection have been determined as 1.4 and 0.17° for AlN/C_α(100), 0.55° and 0.11° for AlN/C_α(111), as well as 0.51 and 0.05° for an AlN/sapphire (0001) reference sample grown under similar conditions. Thus, the crystal quality of AlN on C_α(111) is close to that of AlN on sapphire. The corresponding AlN rms roughness values found by AFM are 1.9 nm on C_α(100), 1.7 nm on C_α(111), and 3.2 nm on sapphire (0001), respectively. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]